Flexible, stretchable coiled-sheet stent

Abstract

A coiled-sheet stent includes a tubular body having a longitudinal axis and a circumference, and a plurality of cylindrical bands formed in the tubular body, each band having a zig-zag pattern including a series of sequential diagonal elements connected to one another and extending about the circumference. A plurality of longitudinal connectors extend between and connect adjacent bands. The diagonal elements have an arcuate shape, all diagonal elements in each band being oriented in either a clockwise or counter-clockwise direction about the circumference. The tubular body is expandable between contracted and enlarged conditions, and the zig-zag pattern is expandable between unstretched and unstretched conditions, the zig-zag pattern being biased towards the stretched condition above a transition temperature, thereby at least partially defining the enlarged condition. A multi-cellular stent structure is also provided that includes a plurality of bat shaped cells formed in a tubular body, each cell defining a head region, a tail region and opposing curved wing regions, and a plurality of connectors extending between and connecting adjacent cells. The head and tail regions of adjacent cells are directly connected to one another, and connectors extend between adjacent wing regions of adjacent cells.

Description

[0001]This application is a continuation of application Ser. No. 09 / 347,845, filed Sep. 30, 1999, now abandoned the disclosure of which is expressly incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates generally to prostheses for implantation within body lumens, and more particularly to a coiled-sheet stent including a stretchable mesh design.BACKGROUND[0003]Tubular prostheses or “stents” are often implanted within blood vessels, for example, within the coronary and carotid arteries, for treating atherosclerotic disease which may involve one or more stenoses. Stents generally have a tubular shape capable of assuming a radially contracted condition to facilitate introduction into a patient's vasculature, and an enlarged condition for engaging the vessel wall at a treatment location. In its contracted condition, the stent may be placed on or in a delivery device, such as a catheter, percutaneously introduced into a patient's vasculature and advanc...

AI Technical Summary

Benefits of technology

[0011]The diagonal elements have a generally arcuate shape, all diagonal elements in each band being oriented in either a clockwise or counter-clockwise direction about the circumference for facilitating packing of the diagonal elements in each band with one another. In a preferred form, each diagonal element includes first and second generally straight portions having first and second ends, the second ends being connected together by a curved portion, the first ends being connected to preceding and succeeding diagonal elements in the zig-zag pattern.

[0013]The tubular body is generally expandable between a contracted condition for facilitating introduction into a body lumen, and an enlarged condition for engaging a wall of a body lumen. Preferably, the tubular body is biased towards the enlarged condition. More preferably, the zig-zag pattern is expandable between an unstretched condition and a stretched condition, the zig-zag pattern being biased towards the stretched condition above a transition temperature which is substantially below body temperature, thereby at least partially defining the enlarged condition. Thus, ends of adjacent diagonal elements may be arranged further away from one another about the circumference in the stretched condition than in the unstretched condition. Further, the diagonal elements may have a less arcuate shape in the stretched condition than in the unstretched condition such that the diagonal elements at least partially straighten for minimizing foreshortening of the tubular body along the longitudinal axis.

[0018]The curved wing regions or arcuate diagonal elements are an important feature of a stent in accordance with the present invention as they significantly improve the flexibility of the resulting stent. Conventional coiled-sheet stents, for example, have substantially rigid lattice structures which may not be as flexible transverse to the longitudinal axis of the stent as desired. In contrast, the arcuate diagonal elements of the present invention facilitate flexing of the individual cells generally transverse to the longitudinal axis, the arcuate diagonal elements extending or compressing as needed to facilitate bending of the stent. Thus, the stent may conform more easily to tortuous body regions through which the stent is directed or within which the stent is implanted. In addition, the arcuate diagonal elements may also reduce foreshortening of the stent during expansion.

Problems solved by technology

Plastically deformable stents, however, may not expand uniformly and may not provide a desired delivery profile because of the need for a balloon on the delivery device underlying the stent.

Such stents, however, may not provide as small a delivery profile as desired and may not anchor against the wall of a vessel as securely as desired, which may lead to migration of the stent within the vessel.

A coiled-sheet stent, however, may be more rigid transverse to its longitudinal axis than tubular stents, potentially resulting in a less flexible stent, which may not be implanted as effectively in tortuous anatomical conditions.

Further, because the lattice-like structure of coiled-sheet stents is substantially nondeformable, if the stent is subjected to radially compressive forces, e.g., when the vessel wall attempts to contract, the stent may tend to buckle rather than recoil from the stress.

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